One of my houseplants has several small, yellow mushrooms on the surface of the potting soil. Will the mushrooms harm the plant?
The small, yellow mushroom is probably Leucocoprinus birnbaumii. The fungus is sometimes referred to as yellow houseplant mushroom, yellow parasol, or flower pot parasol. This species can be found outside in summer, but is most commonly found year-round with potted plants or in greenhouses. The small, lemon yellow mushrooms are about 1 to 3 inches tall with 1 to 2 inch oval or bell-shaped caps. They may appear singly or in clusters.
The Leucocoprinus birnbaumii fungus breaks down dead organic matter in the potting soil. It does not harm living plants. However, the mushrooms are regarded as poisonous to people and animals. If pets or small children reside in the home, it would be wise to remove the mushrooms as they appear. Fungicide treatments are generally not effective against mushrooms.